The invention relates to a method and a device for thread division on a sectional warping machine, according to the preamble of claim 1 and claim 11 respectively. Such a method and such a device serve for separating individual groups of warp threads on winding onto the warping drum, in order to obtain a neat thread arrangement. The method is suitable for the automatic insertion of thread crossing and sizing dividing elements.
The insertion of a dividing cord originally carried out manually, for a long time has been carried out automatically. With this various methods and devices have become known.
EP A 368 801 describes a method with which two parallel individual sections via a dividing cord are introduced into the opened thread warp. Subsequently the sections on both sides of the divided shed warp are connected to one another. The simultaneous introduction of the individual sections is effected by two rod-like holding elements arranged at a distance to one another. The finished dividing element or the two individual sections are with this preferably formed by a plastic web which is weldable and does not need to be knotted. Such dividing elements are however not suitable for all application purposes.
DE A 44 43 627 describes a method with which a dividing cord is drawn in automatically with the help of a cord pull rod. For grasping the dividing cord this is suctioned through a suction tube. With this device however a dividing cord loop may not be layed around a shed warp in a single working procedure.
JP B 62-2055 describes a device which consists of two parallel thread tubes and which may be moved into an opened shed. In the completely moved-in position the two tube ends are connected to one another by a semicircular connection bow open on the inner side. The dividing cord by way of an airflow is introduced into the one thread tube, is turned round at the connection bow and in the neighbouring thread tube is led back again. The connection bow is rigidly arranged and because it is opened on the inner side the dividing cord may slide out with the traversing back of the two parallel thread tubes. A disadvantage however lies in the fact that the open connection bow causes a great pressure drop with the pneumatic conveying of the dividing cord. Furthermore the two thread tubes and the connection bow must always be exactly aligned to one another in order to guarantee a frictionless cord deflection.
By way of the narrow distance of the two thread tubes the thread crossing must be divided at a very steep angle. By way of this a clear dividing of the upper and lower thread position is not securely guaranteed.
On replacing the cord loops which are applied in webs on beaming through two through-going cords on account of the cord loops lying close next to one another the neat thread dividing is hardly possible with certain materials (hairiness).
A further disadvantage lies in the fact that the cord loops independently of the web width are always equally long. By way of this the cord loop is designed for the maximum web width. With smaller web widths the cord loop is much too long and is overwound by the next web. With beaming this has the result that the cord loops remain hanging and thread breakages arise.
It is therefore the object of the invention to provide a method of the above mentioned type with whose help a dividing cord in the simplest manner as a cord loop may be layed around a divided shed warp. The method is to be largely automisable with a low succeptibility to breakdown. The device should be simple to operate and it should also be suitable where appropriate for the retrofitting of existing sectional warping installations. Furthermore with various web widths there are to be able to be applied or manufactured dividing cord loops with always the same overlength.
This object according to the invention is achieved with a method which has the features of claim 1. With regard to the device the object is achieved by a device with the features of claim 11.
The leading together of the free ends of the two guide arms after the lateral introduction has the advantage that the dividing cord without supplementing auxiliary means may be directly transferred from one guide arm to the other guide arm. After the introduction of the dividing cord the free ends are again opened so far that a retraction of the introduction element is possible. With this with a further drawing-off of dividing cord, a cord loop is layed around the divided shed warp. The two guide arms function completely autonomously and a precise alignment to other components is not necessary.
The guide arms are advantageously tubes which on bringing together the two ends are connected into a through-going flow channel, wherein the dividing cord is drawn off by way of an airflow in the flow channel. Since the free tube ends are directly brought together there arises no pressure loss at the turning point of the dividing cord. The pressurised air consumption may therefore be kept relatively low. The air flow may for example be produced by applying a vacuum at, in relation to the flow direction, the output of the second guide arm. In certain cases the conveying of the dividing cord may however also be effected purely mechanically. With a sufficient stiffness it would also be conceivable to advance the dividing cord with the help of pinch rollers.
Since with a sectional warping process as a rule numerous dividing cord loops must be inserted, the method functions particularly rationally when an inserted cord loop of the introduction element is separated from the sections of the dividing cord still lying in the guide arms and when with the subsequent insertion procedure the dividing cord section lying in the second guide arm is led away together with the leading-back of a new dividing cord. Evidently the dividing cord remains, in this manner, need not be manually removed. That dividing cord section which remains in the first guide arm is already the beginning of the following dividing cord which with the next-following procedure is pneumatically transported into the second guide arm. The introduction element is advantageously moved on a linear advance path. Thus one may always insert to the suitable web width without carrying out an adaptation of the tube lengths.
After the retraction of the introduction element a knotting apparatus for knotting the cord loop is pushed into the region of the advance path, and after the knotting and separating off of the cord loop, is again retracted. In this manner also the knotting need not be carried out manually and the knotting apparatus may be placed exactly in the correct region without it impeding the introduction element. For this purpose it is particularly advantageous when the knotting apparatus on a flexible push element is displaced out of a rest position on a curved path into a knotting position. By way of this the knotting apparatus may be arranged in a space-saving manner below the advance plane of the introduction element.
Further advantages may be achieved when the knotted cord loop by way of a positioning and tensioning device is aligned in a manner such that the cord loop bears at least on one side on the divided shed warp or on the warp web. By way of this it is prevented that a laterally protruding cord loop is overwound by the next warp web. Thus on beaming it is prevented that the cord loops remain hanging and thread breakages arise. The alignment of the cord loops is effected advantageously contactless by way of a suction device or by way of a blowing device. Such a positioning and tensioning process could however also advantageously be applied with manual sectional warping machines for positioning and tensioning the cord loop.
It is furthermore advantageous when the cord loop is applied on the divided shed warp in a manner such that with the subsequent beaming process the cord loop lies on the outer side, i.e. above, which considerably simplifies the accessibility.
With the device according to the invention both guide arms are movably mounted in a manner such that their free ends are guidable together in a preferably pincer-like movement. With this it is advantageous when at least one of the two guide arms is pivotably mounted and when with a pressure means cylinder it may be moved to and from the neighbouring guide arm. For this a simple turning joint is sufficient, wherein only a relatively small pivoting angle must be covered in order the lead together the free ends. Alternatively the guide arms could however also be parallely led together or opened.
The two guide arms are preferably designed as tubes whose free ends after the bringing together form a closed hollow bow. Thus there arises a U-shaped flow channel in which unhindered a dividing cord may be advanced. The advance is effected with this with air conveyor apparatus (Air Mover) which for producing an air flow is in acting connection with the tubes. The first guide arm may with this at the entry be connected to a cord supply container and at the exit of the second guide arm there may be arranged an air conveyor apparatus for producing a vacuum in the tubes. Since the tubes together with the cord supply container form a closed channel system, the dividing cord may be drawn off in a simple manner and with a low energy expense.
The introduction element is advantageously mounted on a carriage, and along a linear advance path is introducable into the shed warp. In the region of the advance path there is a knotting apparatus displaceable preferably with the help of a flexible push element and along a curved path between a rest position and a knotting position.